﻿using System;
using System.Runtime.InteropServices;

/*
The MIT License (MIT)

Copyright (c) 2014 Justin Murray

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

// This File (C): https://github.com/murrayju/CreateProcessAsUser, MIT

namespace InstallerBaseWixSharp.Files.PInvoke
{
    public static class ProcessExtensions
    {
        #region Win32 Constants

        private const int CREATE_UNICODE_ENVIRONMENT = 0x00000400;
        private const int CREATE_NO_WINDOW = 0x08000000;

        private const int CREATE_NEW_CONSOLE = 0x00000010;

        private const uint INVALID_SESSION_ID = 0xFFFFFFFF;
        private static readonly IntPtr WTS_CURRENT_SERVER_HANDLE = IntPtr.Zero;

        #endregion

        #region DllImports

        [DllImport("advapi32.dll", EntryPoint = "CreateProcessAsUser", SetLastError = true, CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
        private static extern bool CreateProcessAsUser(
            IntPtr hToken,
            String lpApplicationName,
            String lpCommandLine,
            IntPtr lpProcessAttributes,
            IntPtr lpThreadAttributes,
            bool bInheritHandle,
            uint dwCreationFlags,
            IntPtr lpEnvironment,
            String lpCurrentDirectory,
            ref STARTUPINFO lpStartupInfo,
            out PROCESS_INFORMATION lpProcessInformation);

        [DllImport("advapi32.dll", EntryPoint = "DuplicateTokenEx")]
        private static extern bool DuplicateTokenEx(
            IntPtr ExistingTokenHandle,
            uint dwDesiredAccess,
            IntPtr lpThreadAttributes,
            int TokenType,
            int ImpersonationLevel,
            ref IntPtr DuplicateTokenHandle);

        [DllImport("userenv.dll", SetLastError = true)]
        private static extern bool CreateEnvironmentBlock(ref IntPtr lpEnvironment, IntPtr hToken, bool bInherit);

        [DllImport("userenv.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool DestroyEnvironmentBlock(IntPtr lpEnvironment);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern bool CloseHandle(IntPtr hSnapshot);

        [DllImport("kernel32.dll")]
        private static extern uint WTSGetActiveConsoleSessionId();

        [DllImport("Wtsapi32.dll")]
        private static extern uint WTSQueryUserToken(uint SessionId, ref IntPtr phToken);

        [DllImport("wtsapi32.dll", SetLastError = true)]
        private static extern int WTSEnumerateSessions(
            IntPtr hServer,
            int Reserved,
            int Version,
            ref IntPtr ppSessionInfo,
            ref int pCount);

        #endregion

        #region Win32 Structs

        private enum SW
        {
            SW_HIDE = 0,
            SW_SHOWNORMAL = 1,
            SW_NORMAL = 1,
            SW_SHOWMINIMIZED = 2,
            SW_SHOWMAXIMIZED = 3,
            SW_MAXIMIZE = 3,
            SW_SHOWNOACTIVATE = 4,
            SW_SHOW = 5,
            SW_MINIMIZE = 6,
            SW_SHOWMINNOACTIVE = 7,
            SW_SHOWNA = 8,
            SW_RESTORE = 9,
            SW_SHOWDEFAULT = 10,
            SW_MAX = 10,
        }

        private enum WTS_CONNECTSTATE_CLASS
        {
            WTSActive,
            WTSConnected,
            WTSConnectQuery,
            WTSShadow,
            WTSDisconnected,
            WTSIdle,
            WTSListen,
            WTSReset,
            WTSDown,
            WTSInit,
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct PROCESS_INFORMATION
        {
            public IntPtr hProcess;
            public IntPtr hThread;
            public uint dwProcessId;
            public uint dwThreadId;
        }

        private enum SECURITY_IMPERSONATION_LEVEL
        {
            SecurityAnonymous = 0,
            SecurityIdentification = 1,
            SecurityImpersonation = 2,
            SecurityDelegation = 3,
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct STARTUPINFO
        {
            public int cb;
            public String lpReserved;
            public String lpDesktop;
            public String lpTitle;
            public uint dwX;
            public uint dwY;
            public uint dwXSize;
            public uint dwYSize;
            public uint dwXCountChars;
            public uint dwYCountChars;
            public uint dwFillAttribute;
            public uint dwFlags;
            public short wShowWindow;
            public short cbReserved2;
            public IntPtr lpReserved2;
            public IntPtr hStdInput;
            public IntPtr hStdOutput;
            public IntPtr hStdError;
        }

        private enum TOKEN_TYPE
        {
            TokenPrimary = 1,
            TokenImpersonation = 2,
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct WTS_SESSION_INFO
        {
            public readonly UInt32 SessionID;

            [MarshalAs(UnmanagedType.LPStr)]
            public readonly String pWinStationName;

            public readonly WTS_CONNECTSTATE_CLASS State;
        }

        #endregion

        // Gets the user token from the currently active session
        private static bool GetSessionUserToken(ref IntPtr phUserToken)
        {
            var bResult = false;
            var hImpersonationToken = IntPtr.Zero;
            var activeSessionId = INVALID_SESSION_ID;
            var pSessionInfo = IntPtr.Zero;
            var sessionCount = 0;

            // Get a handle to the user access token for the current active session.
            if (WTSEnumerateSessions(WTS_CURRENT_SERVER_HANDLE, 0, 1, ref pSessionInfo, ref sessionCount) != 0)
            {
                var arrayElementSize = Marshal.SizeOf(typeof(WTS_SESSION_INFO));
                var current = pSessionInfo;

                for (var i = 0; i < sessionCount; i++)
                {
                    var si = (WTS_SESSION_INFO)Marshal.PtrToStructure((IntPtr)current, typeof(WTS_SESSION_INFO));
                    current += arrayElementSize;

                    if (si.State == WTS_CONNECTSTATE_CLASS.WTSActive)
                    {
                        activeSessionId = si.SessionID;
                    }
                }
            }

            // If enumerating did not work, fall back to the old method
            if (activeSessionId == INVALID_SESSION_ID)
            {
                activeSessionId = WTSGetActiveConsoleSessionId();
            }

            if (WTSQueryUserToken(activeSessionId, ref hImpersonationToken) != 0)
            {
                // Convert the impersonation token to a primary token
                bResult = DuplicateTokenEx(hImpersonationToken, 0, IntPtr.Zero,
                    (int)SECURITY_IMPERSONATION_LEVEL.SecurityImpersonation, (int)TOKEN_TYPE.TokenPrimary,
                    ref phUserToken);

                CloseHandle(hImpersonationToken);
            }

            return bResult;
        }

        public static bool StartProcessAsCurrentUser(string appPath, string cmdLine = null, string workDir = null, bool visible = true)
        {
            var hUserToken = IntPtr.Zero;
            var startInfo = new STARTUPINFO();
            var procInfo = new PROCESS_INFORMATION();
            var pEnv = IntPtr.Zero;
            int iResultOfCreateProcessAsUser;

            startInfo.cb = Marshal.SizeOf(typeof(STARTUPINFO));

            try
            {
                if (!GetSessionUserToken(ref hUserToken))
                {
                    throw new Exception("StartProcessAsCurrentUser: GetSessionUserToken failed.");
                }

                uint dwCreationFlags = CREATE_UNICODE_ENVIRONMENT | (uint)(visible ? CREATE_NEW_CONSOLE : CREATE_NO_WINDOW);
                startInfo.wShowWindow = (short)(visible ? SW.SW_SHOW : SW.SW_HIDE);
                startInfo.lpDesktop = "winsta0\\default";

                if (!CreateEnvironmentBlock(ref pEnv, hUserToken, false))
                {
                    throw new Exception("StartProcessAsCurrentUser: CreateEnvironmentBlock failed.");
                }

                if (!CreateProcessAsUser(hUserToken,
                    appPath, // Application Name
                    cmdLine, // Command Line
                    IntPtr.Zero,
                    IntPtr.Zero,
                    false,
                    dwCreationFlags,
                    pEnv,
                    workDir, // Working directory
                    ref startInfo,
                    out procInfo))
                {
                    iResultOfCreateProcessAsUser = Marshal.GetLastWin32Error();
                    throw new Exception("StartProcessAsCurrentUser: CreateProcessAsUser failed.  Error Code -" + iResultOfCreateProcessAsUser);
                }

                iResultOfCreateProcessAsUser = Marshal.GetLastWin32Error();
            }
            finally
            {
                CloseHandle(hUserToken);
                if (pEnv != IntPtr.Zero)
                {
                    DestroyEnvironmentBlock(pEnv);
                }
                CloseHandle(procInfo.hThread);
                CloseHandle(procInfo.hProcess);
            }

            return true;
        }

    }
}
